Celadon Gym is stationed herein—the fourth gym in Kanto's successional line of gym-leaders wherein the Rainbow Badge is conferred to victorious challengers. Because Team Rocket agents are initially marshaled throughout the city, various pathways are impassable; this includes Celadon Gym, thereby necessitating that the Celadon Rocket Hideout quest is completed in order for them to vacate the area and deobstruct the pathways.

It is considered the most metropolitan city in the Kanto region, being the most architecturally developed city in it. In addition to the aforementioned gym, the city's tract includes Celadon Department Store, an office complex, and Celadon Game Corner.

Notable miscellanies

By the juncture that the player has arrived at Celadon City, Team Rocket has already commandeered a secret hideout, as they have used Celadon Gaming Corner's substories as a surreptitious operational base.

Since Team Rocket agents are obstructively marshaled throughout the city, the player's regional travels will not be progressible until the quest is completed, since the gym is unreachable before then. Once the player and the police's investigatory team have apprehended the base, which culminates in defeating Giovanni, the criminal organization will abscond out of the city to search for a new base.

Celadon Department Store

Celadon Department Store is the only department store in Kanto, being the most all-encompassing store of Pokémon-trainer paraphernalia available. In addition to Pokémon apparatus and supplements, it is also the only emporium in Kanto to sell TMs.

Celadon Subway

Celadon City is one of the seven destinational outlets available in Kanto's intraregional-subway system, thereby providing an expeditious shortcut to this area and to six other destinations from it.

Celadon Office

Celadon Office is a three-story complex, serving as a data-process facility for various data-processing functions; that includes a receptionist who calculatively counts your Pokémon's total IVs and a boss-NPC cooldown-checker on the second floor.

On the third floor exists a bevy of staff-member spoofs who are portrayed as clerical workers, using their computers to submit content-developmental creations. Interacting with Tiggus and promptedly agreeing with his praise of the staff members will reward you one Soothe Bell.

Celadon Game Corner

While Celadon Game Corner has not been functionalized as a gaming venue, meaning that the slot machines are inoperable and that there is no prize-center adjunct, it is noteworthy because a TM-tutor is stationed herein to impart the following TM techniques: Steel Wing, Charge Beam, Giga Impact, and Sludge Wave.

Trainer Red

After defeating the Celadon Gym, Trainer Red will be blocking the exit, forcing the player to challenge him. He will only have a Pikachu, but a strong one that is meant to be lost to, especially after being exhausted from a Gym battle.

Emboldened moves avail from a STAB bonus when deployed by that Pokémon.

Italicized moves are functionally broken; see their individualized pages for more information.

Officer Jenny's bounties

Just like in Viridian City, there is an Officer that gives small quests called "bounties". Found in the square in front of the Department Store, she gives the following bounties:

Fight Michael: This bounty requires the player to fight Michael in Route 17. By his location, it will be necessary for the player to obtain a Bicycle first. Michael will be staying near the north exit of the route. Once spoken to, he will fight the player with a team of 4 Pokemon of level close to 35. These Pokemon also all hold items to go along with their moveset or ability. Once defeated, Michael will disappear and the player will be able to report back to Jenny. The reward for completing this bounty is 10,000 and a Bright Powder.

Buy an HP Up: This bounty requires the player to go to the nearby Department Store and purchase an HP Up. The HP Up however doesn't require to buy one, and can be obtained from other sources. It will be removed from the player's inventory when completing the quest. The reward for completing this bounty is 14,000, resulting in a net gain of 6,000 if the HP Up was purchased.

The player may accept any bounty at the same time, but each bounty can only be completed once.

The Honey Tree in Celadon City is located in the north-west corner of the city. By spreading Honey onto the tree, a random wild Pokemon will appear, and the tree will enter a cooldown of 24 hours. This Honey Tree is categorized as a Grass tree; spreading Honey to multiple Grass Honey Trees in a row will reward with stronger Grass type Pokemon.

Shrouded underneath a tree left to the Cut tree on the way to the gym.

Celadon Gym

Upon defeating Erika, you will procure the Rainbow Badge.

Additionally, the gym-greeter will sell you TM21 (Mega Drain) in quantities of 1 for 1,500 and 5 for 6,000.

Due to Team Rocket agents occluding the pathway to it, you will need to complete the Celadon Rocket Hideout quest in order for the pathway thereto to be navigable.

NPCs

Erika

As a Grass-type specialist, Fire and Flying-type Pokémon will be the most type-advantageous against her lineup. Growlithe and Vulpix are the most handily huntable Fire-type Pokémon to deploy against her, as they spawn on the contiguous routes.

Since all her Pokémon are also dual-types with a secondary type of Poison, it would also be judicious to entertain the deployment Pokémon and moves that are type-advantageous against it, such as the Psychic type.